The Epsilon Eridani system is a young system estimated at something less than one billion years in age. Native life on Pelayo had reached the stage where the planets atmosphere had been converted to a nitrogen/oxygen mix and simple animal forms were also found on the world.

When human colonists from Earth arrived in 2214 on board the sub-light colony transport CT-3 Far Horizon, they were surprised to find extensive native life. Only recently has this been revealed that this was the result of the Thalor seeding the world with life forms from other worlds within their then sphere. When these species are added to those brought by the colonists Pelayo ended up with a very diverse biosphere.

The colonists settling on Pelayo were chiefly drawn from the southern regions of Europe, in particular Spain, Southern France and Italy. The population of the colony grew rapidly over the following years, being supplemented by occassional arrivals of smaller sub-light transports bringing new colonists. These did not always integrate very well and some conflict arose as a result.

In general though the Pelayo colony prospered. When Earth began producing faster than light ships with the new Hyperspace Translation Drive occassional transports from Earth began to turn up. Luckily for Pelayo perhaps, Earth and the Federated States of Sol, became involved in the botched military campaign against the Alpha Centuari colonies and could not afford a war on two fronts. Pelayo and The Federated States managed to keep cordial relations with each other, This was carried over into relations with the newly formed United Worlds Commonwealth.

In 2525 Pelayo was offered membership in the United Worlds Commonwealth, but declined, the hyperspace beacon network was not complete and no deep space station way point had yet been completed between the two regions making FTL travel much more hazardous.

In 2638 war broke out between the United Worlds Commonwealth and the Das Sternum Reich. This war raged for three years. Initially Pelayo was untouched, but late in 2639 a Reich raider launched an attack against Pelayo. The raid was driven off with minor losses. Intelligence revealed that the raid had been launched from the Tau Ceti system in which the Reich had placed a small garrison. In the only offensive action carried out by Pelayo during the UWC/Reich war, the Pelayons assembled a task force using a number of small warships and merchant transports and headed for Tau Ceti. The Pelayon assault took the Reich garrison by surprise and it was forced to flee or surrender. The main world in Tau Ceti was occupied by Pelayon forces until 2642 at which time the Tau Ceti systems worlds became independent.

In 2650 an agreement was drawn up between the various worlds of the Epsilon Eridani system, including Pelayo and some neighbouring systems, including Tau Ceti, which resulted in the creation of a mutual defence pact. In part this was done in response to the perceived threat of further Reich aggression. This formed the Eridani Alliance, the agreement to which was signed on Pelayo in 2651.

The Eridani Alliance is not a true state in the sense that the United Worlds Commonwealth is, instead it is a defence pact allowing for mutual defence and standardisation of military hardware and training regimes. The worlds which make up the alliance are still free to govern their own affairs. Though as a result of history the Alliance is dominated by the worlds of Pelayo in Epsilon Eridani and Beiro in Tau Ceti.

Technologically Pelayo has a largely stable tech level 10 base in most areas. However in the biotech areas Pelayo has forged ahead and has achieved a borderline tech level 12 in the medical areas.